List all files in a directory in Node.js recursively in a synchronous fashion

walksync.js

// List all files in a directory in Node.js recursively in a synchronous fashion
var walkSync = function(dir, filelist) {
  var fs = fs || require('fs'),
      files = fs.readdirSync(dir);
  filelist = filelist || [];
  files.forEach(function(file) {
    if (fs.statSync(dir + file).isDirectory()) {
      filelist = walkSync(dir + file + '/', filelist);
    }
    else {
      filelist.push(file);
    }
  });
  return filelist;
};

Node v20.1+

const filelist = await fs.readdir(dir, { recursive: true });